Prevalence of monogenic diabetes in the population-based Norwegian Childhood Diabetes Registry

Two novel GCK mutations in Chinese patients with maturity-onset diabetes of the young

PURPOSE

Heterozygous inactivating mutations in the glucokinase (GCK) gene result in the asymptomatic fasting hyperglycemia named as GCK-MODY or MODY2. The genetic testing can effectively avoid the misdiagnosis and inappropriate treatment for GCK-MODY.

METHODS

A total of 25 unrelated families with MODY were screened for mutations in coding region of GCK by using direct sequencing. Three different bioinformatics tools such as PolyPhen2, Mutation Taster and PROVEAN were performed to predict the function of mutant proteins. The glucose profile was recorded by continuous glucose monitoring system (CGMS) to evaluate the glycemic variability for the GCK-MODY patient.

RESULTS

Our study identified five GCK mutations in 24% of the families (6/25): two novel mutations (I126fs and G385A) and three already described mutations (G44S, H50fs and S383L). In silico analyses predicted that these mutations altered structural conformational changes. The values of mean amplitude of glycemic excursions (MAGE), an important index of blood glucose fluctuation in CGMS system, were 0.81 in the first 24 h and 1.61 in the second 24 h record in the patient with GCK-MODY (F3), suggesting little glucose fluctuation.

CONCLUSION

The genetic testing is suggested to be important to differentiate GCK-MODY from other types of diabetes. CGMS might be used to screen GCK-MODY cases prior to genetic testing.

Paediatric diabetes subtypes in a consanguineous population: a single-centre cohort study from Kurdistan, Iraq

AIMS/HYPOTHESIS

Monogenic diabetes is estimated to account for 1-6% of paediatric diabetes cases in primarily non-consanguineous populations, while the incidence and genetic spectrum in consanguineous regions are insufficiently defined. In this single-centre study we aimed to evaluate diabetes subtypes, obtain the consanguinity rate and study the genetic background of individuals with syndromic and neonatal diabetes in a population with a high rate of consanguinity.

METHODS

Data collection was carried out cross-sectionally in November 2021 at the paediatric diabetic clinic, Dr Jamal Ahmad Rashed Hospital, in Sulaimani, Kurdistan, Iraq. At the time of data collection, 754 individuals with diabetes (381 boys) aged up to 16 years were registered. Relevant participant data was obtained from patient files. Consanguinity status was known in 735 (97.5%) participants. Furthermore, 12 families of children with neonatal diabetes and seven families of children with syndromic diabetes consented to genetic testing by next-generation sequencing. Prioritised variants were evaluated using the American College of Medical Genetics and Genomics guidelines and confirmed by Sanger sequencing.

RESULTS

A total of 269 of 735 participants (36.5%) with known consanguinity status were offspring of consanguineous families. An overwhelming majority of participants (714/754, 94.7%) had clinically defined type 1 diabetes (35% of them were born to consanguineous parents), whereas only eight (1.1%) had type 2 diabetes (38% consanguineous). Fourteen (1.9%) had neonatal diabetes (50% consanguineous), seven (0.9%) had syndromic diabetes (100% consanguineous) and 11 (1.5%) had clinically defined MODY (18% consanguineous). We found that consanguinity was significantly associated with syndromic diabetes (p=0.0023) but not with any other diabetes subtype. The genetic cause was elucidated in ten of 12 participants with neonatal diabetes who consented to genetic testing (homozygous variants in GLIS3 [sibling pair], PTF1A and ZNF808 and heterozygous variants in ABCC8 and INS) and four of seven participants with syndromic diabetes (homozygous variants in INSR, SLC29A3 and WFS1 [sibling pair]). In addition, a participant referred as syndromic diabetes was diagnosed with mucolipidosis gamma and probably has type 2 diabetes.

CONCLUSIONS/INTERPRETATION

This unique single-centre study confirms that, even in a highly consanguineous population, clinically defined type 1 diabetes is the prevailing paediatric diabetes subtype. Furthermore, a pathogenic cause of monogenic diabetes was identified in 83% of tested participants with neonatal diabetes and 57% of participants with syndromic diabetes, with most variants being homozygous. Causative genes in our consanguineous participants were markedly different from genes reported from non-consanguineous populations and also from those reported in other consanguineous populations. To correctly diagnose syndromic diabetes in consanguineous populations, it may be necessary to re-evaluate diagnostic criteria and include additional phenotypic features such as short stature and hepatosplenomegaly.

Characterisation of HNF1A variants in paediatric diabetes in Norway using functional and clinical investigations to unmask phenotype and monogenic diabetes

AIMS/HYPOTHESIS

Correctly diagnosing MODY is important, as individuals with this diagnosis can discontinue insulin injections; however, many people are misdiagnosed. We aimed to develop a robust approach for determining the pathogenicity of variants of uncertain significance in hepatocyte nuclear factor-1 alpha (HNF1A)-MODY and to obtain an accurate estimate of the prevalence of HNF1A-MODY in paediatric cases of diabetes.

METHODS

We extended our previous screening of the Norwegian Childhood Diabetes Registry by 830 additional samples and comprehensively genotyped HNF1A variants in autoantibody-negative participants using next-generation sequencing. Carriers of pathogenic variants were treated by local healthcare providers, and participants with novel likely pathogenic variants and variants of uncertain significance were enrolled in an investigator-initiated, non-randomised, open-label pilot study (ClinicalTrials.gov registration no. NCT04239586). To identify variants associated with HNF1A-MODY, we functionally characterised their pathogenicity and assessed the carriers' phenotype and treatment response to sulfonylurea.

RESULTS

In total, 615 autoantibody-negative participants among 4712 cases of paediatric diabetes underwent genetic sequencing, revealing 19 with HNF1A variants. We identified nine carriers with novel variants classified as variants of uncertain significance or likely to be pathogenic, while the remaining ten participants carried five pathogenic variants previously reported. Of the nine carriers with novel variants, six responded favourably to sulfonylurea. Functional investigations revealed their variants to be dysfunctional and demonstrated a correlation with the resulting phenotype, providing evidence for reclassifying these variants as pathogenic.

CONCLUSIONS/INTERPRETATION

Based on this robust classification, we estimate that the prevalence of HNF1A-MODY is 0.3% in paediatric diabetes. Clinical phenotyping is challenging and functional investigations provide a strong complementary line of evidence. We demonstrate here that combining clinical phenotyping with functional protein studies provides a powerful tool to obtain a precise diagnosis of HNF1A-MODY.

Genetic testing for misclassified monogenic diabetes in Māori and Pacific peoples in Aōtearoa New Zealand with early-onset type 2 diabetes

Aims

Monogenic diabetes accounts for 1-2% of diabetes cases yet is often misdiagnosed as type 2 diabetes. The aim of this study was to examine in Māori and Pacific adults clinically diagnosed with type 2 diabetes within 40 years of age, (a) the prevalence of monogenic diabetes in this population (b) the prevalence of beta-cell autoantibodies and (c) the pre-test probability of monogenic diabetes.

Methods

Targeted sequencing data of 38 known monogenic diabetes genes was analyzed in 199 Māori and Pacific peoples with BMI of 37.9 ± 8.6 kg/m² who had been diagnosed with type 2 diabetes between 3 and 40 years of age. A triple-screen combined autoantibody assay was used to test for GAD, IA-2, and ZnT8. MODY probability calculator score was generated in those with sufficient clinical information (55/199).

Results

No genetic variants curated as likely pathogenic or pathogenic were found. One individual (1/199) tested positive for GAD/IA-2/ZnT8 antibodies. The pre-test probability of monogenic diabetes was calculated in 55 individuals with 17/55 (31%) scoring above the 20% threshold considered for diagnostic testing referral.

Discussion

Our findings suggest that monogenic diabetes is rare in Māori and Pacific people with clinical age, and the MODY probability calculator likely overestimates the likelihood of a monogenic cause for diabetes in this population.

Prescriptions for insulin and insulin analogues in children with and without major congenital anomalies: a data linkage cohort study across six European regions

Are children with major congenital anomalies more likely to develop diabetes requiring insulin therapy, as indicated by prescriptions for insulin, than children without congenital anomalies? The aim of this study is to evaluate prescription rates of insulin/insulin analogues in children aged 0-9 years with and without major congenital anomalies. A EUROlinkCAT data linkage cohort study, involving six population-based congenital anomaly registries in five countries. Data on children with major congenital anomalies (60,662) and children without congenital anomalies (1,722,912), the reference group, were linked to prescription records. Birth cohort and gestational age were examined. The mean follow-up for all children was 6.2 years. In children with congenital anomalies aged 0-3 years, 0.04 per 100 child-years (95% CIs 0.01-0.07) had > 1 prescription for insulin/insulin analogues compared with 0.03 (95% CIs 0.01-0.06) in reference children, increasing ten-fold by age 8-9 years. The risk of > 1 prescription for insulin/insulin analogues aged 0-9 years in children with non-chromosomal anomalies (RR 0.92, 95% CI 0.84-1.00) was similar to that of reference children. However, children with chromosomal anomalies (RR 2.37, 95% CI 1.91-2.96), and specifically children with Down syndrome (RR 3.44, 95% CIs 2.70-4.37), Down syndrome with congenital heart defects (RR 3.86, 95% CIs 2.88-5.16) and Down syndrome without congenital heart defects (RR 2.78, 95% CIs 1.82-4.27), had a significantly increased risk of > 1 prescription for insulin/insulin analogues aged 0-9 years compared to reference children. Female children had a reduced risk of > 1 prescription aged 0-9 years compared with male children (RR 0.76, 95% CI 0.64-0.90 for children with congenital anomalies and RR 0.90, 95% CI 0.87-0.93 for reference children). Children without congenital anomalies born preterm (< 37 weeks) were more likely to have > 1 insulin/insulin analogue prescription compared to term births (RR 1.28, 95% CIs 1.20-1.36).

CONCLUSION

This is the first population-based study using a standardised methodology across multiple countries. Males, children without congenital anomalies born preterm and those with chromosomal anomalies had an increased risk of being prescribed insulin/insulin analogues. These results will help clinicians to identify which congenital anomalies are associated with an increased risk of developing diabetes requiring insulin therapy and allow them to reassure families of children who have non-chromosomal anomalies that their risk is similar to that of the general population.

WHAT IS KNOWN

• Children and young adults with Down syndrome have an increased risk of diabetes requiring insulin therapy. • Children born prematurely have an increased risk of developing diabetes requiring insulin therapy.

WHAT IS NEW

• Children with non-chromosomal anomalies do not have an increased risk of developing diabetes requiring insulin therapy compared to children without congenital anomalies. • Female children, with or without major congenital anomalies, are less likely to develop diabetes requiring insulin therapy before the age of 10 compared to male children.

Identification of monogenic variants in more than ten per cent of children without type 1 diabetes-related autoantibodies at diagnosis in the Finnish Pediatric Diabetes Register

AIMS/HYPOTHESIS

Monogenic forms of diabetes (MODY, neonatal diabetes mellitus and syndromic forms) are rare, and affected individuals may be misclassified and treated suboptimally. The prevalence of type 1 diabetes is high in Finnish children but systematic screening for monogenic diabetes has not been conducted. We assessed the prevalence and clinical manifestations of monogenic diabetes in children initially registered with type 1 diabetes in the Finnish Pediatric Diabetes Register (FPDR) but who had no type 1 diabetes-related autoantibodies (AABs) or had only low-titre islet cell autoantibodies (ICAs) at diagnosis.

METHODS

The FPDR, covering approximately 90% of newly diagnosed diabetic individuals aged ≤15 years in Finland starting from 2002, includes data on diabetes-associated HLA genotypes and AAB data (ICA, and autoantibodies against insulin, GAD, islet antigen 2 and zinc transporter 8) at diagnosis. A next generation sequencing gene panel including 42 genes was used to identify monogenic diabetes. We interpreted the variants in HNF1A by using the gene-specific standardised criteria and reported pathogenic and likely pathogenic findings only. For other genes, we also reported variants of unknown significance if an individual's phenotype suggested monogenic diabetes.

RESULTS

Out of 6482 participants, we sequenced DNA for 152 (2.3%) testing negative for all AABs and 49 (0.8%) positive only for low-titre ICAs (ICA_low). A monogenic form of diabetes was revealed in 19 (12.5%) of the AAB-negative patients (14 [9.2%] had pathogenic or likely pathogenic variants) and two (4.1%) of the ICA_low group. None had ketoacidosis at diagnosis or carried HLA genotypes conferring high risk for type 1 diabetes. The affected genes were GCK, HNF1A, HNF4A, HNF1B, INS, KCNJ11, RFX6, LMNA and WFS1. A switch from insulin to oral medication was successful in four of five patients with variants in HNF1A, HNF4A or KCNJ11.

CONCLUSIONS/INTERPRETATION

More than 10% of AAB-negative children with newly diagnosed diabetes had a genetic finding associated with monogenic diabetes. Because the genetic diagnosis can lead to major changes in treatment, we recommend referring all AAB-negative paediatric patients with diabetes for genetic testing. Low-titre ICAs in the absence of other AABs does not always indicate a diagnosis of type 1 diabetes.

Genetic and Functional Analyses of the Novel KLF11 Pro193Thr Variant in a Three-Generation Family with MODY7

KLF11 regulates insulin gene expression through binding to the insulin promoter and has been reported as a causative gene for maturity-onset diabetes of the young 7 (MODY7). Here, we report a novel KLF11 variant associated with a three-generation family with early childhood-onset diabetes and explore its clinical and functional characteristics. The three-generational pedigree contains five patients affected by diabetes. The pathogenic variant identified by whole-exome sequencing was further confirmed by Sanger sequencing and pedigree verification. Luciferase reporter assays and glucose-stimulated insulin secretion were used to examine whether the KLF11 variant binds to the insulin promoter and regulate insulin secretion in vitro. The proband, his son, and his uncle exhibited hyperglycemia at ages 32, 13 and 71 years, respectively. All three patients showed characteristics of metabolic syndrome (obesity, dyslipidemia, and diabetes), but the insulin secretion of islet β-cells was impaired. A novel heterozygous missense variant, c.577 C>A (p.Pro193Thr) of the KLF11 gene was detected in all three patients. This variant co-segregates with the diabetes phenotype, consistent with an autosomal dominant disorder. The identified KLF11 p.Pro193Thr variant drastically decreased the transcriptional activity of KLF11, as demonstrated by luciferase reporter assay. Functional analyses revealed that the KLF11 Pro193Thr variant inhibited glucose-stimulated insulin secretion. We identified a novel KLF11 Pro193Thr variant in a three generation family with MODY7. These findings shed light on the molecular mechanisms underlying the pathogenesis of MODY7 and expand the genotype and clinical spectrum of MODY7.

Diabetes-related antibody-testing is a valuable screening tool for identifying monogenic diabetes - A survey from the worldwide SWEET registry

AIMS

To evaluate access to screening tools for monogenic diabetes in paediatric diabetes centres across the world and its impact on diagnosis and clinical outcomes of children and youth with genetic forms of diabetes.

METHODS

79 centres from the SWEET diabetes registry including 53,207 children with diabetes participated in a survey on accessibility and use of diabetes related antibodies, c-peptide and genetic testing.

RESULTS

73, 63 and 62 participating centres had access to c-peptide, antibody and genetic testing, respectively. Access to antibody testing was associated with higher proportion of patients with rare forms of diabetes identified with monogenic diabetes (54 % versus 17 %, p = 0.01), lower average whole clinic HbA1c (7.7[Q1,Q2: 7.3-8.0]%/61[56-64]mmol/mol versus 9.2[8.6-10.0]%/77[70-86]mmol/mol, p < 0.001) and younger age at onset (8.3 [7.3-8.8] versus 9.7 [8.6-12.7] years p < 0.001). Additional access to c-peptide or genetic testing was not related to differences in age at onset or HbA1c outcome.

CONCLUSIONS

Clinical suspicion and antibody testing are related to identification of different types of diabetes. Implementing access to comprehensive antibody screening may provide important information for selecting individuals for further genetic evaluation. In addition, worse overall clinical outcomes in centers with limited diagnostic capabilities indicate they may also need support for individualized diabetes management.

TRIAL REGISTRATION

NCT04427189.

Precision Diabetes: Lessons Learned from Maturity-Onset Diabetes of the Young (MODY)

Maturity‐onset of diabetes of the young (MODY) are monogenic forms of diabetes characterized by early onset diabetes with autosomal dominant inheritance. Since its first description about six decades ago, there have been significant advancements in our understanding of MODY from clinical presentations to molecular diagnostics and therapeutic responses. The prevalence of MODY is estimated as at least 1.1–6.5% of the pediatric diabetes population with a high degree of geographic variability that might arise from several factors in the criteria used to ascertain cases. GCK‐MODY, HNF1A‐MODY, and HNF4A‐MODY account for >90% of MODY cases. While some MODY forms do not require treatment (i.e., GCK‐MODY), some others are highly responsive to oral agents (i.e., HNF1A‐MODY). The risk of micro‐ and macro‐vascular complications of diabetes also differ significantly between MODY forms. Despite its high clinical impact, 50–90% of MODY cases are estimated to be misdiagnosed as type 1 or type 2 diabetes. Although there are many clinical features suggestive of MODY diagnosis, there is no single clinical criterion. An online MODY Risk Calculator can be a useful tool for clinicians in the decision‐making process for MODY genetic testing in some situations. Molecular genetic tests with a commercial gene panel should be performed in cases with a suspicion of MODY. Unresolved atypical cases can be further studied by exome or genome sequencing in a clinical or research setting, as available.

Nine-fold higher risk of acute myocardial infarction in subjects with type 1 diabetes compared to controls in Norway 1973-2017

BACKGROUND

We aimed to study the cumulative incidence and risk factors (sex, age, calendar year of diabetes onset, country of origin and educational level) of acute myocardial infarction (AMI) in subjects with type 1 diabetes and matched controls.

METHODS

A nationwide cohort of subjects with type 1 diabetes diagnosed at age < 15 years in Norway during 1973-2000 was followed until the first AMI event, emigration, death or 31st of December 2017. The Norwegian Childhood Diabetes Registry was linked to five nationwide registries, and up to ten sex- and age-matched controls per case were included.

RESULTS

Among 7086 subjects with type 1 diabetes, 170 (2.4%) were identified with incident AMI, compared to 193 (0.3%) of 69,356 controls. Mean age and diabetes duration at first AMI was 40.8 years and 30.6 years, respectively. The probability of AMI after 40 years of follow-up was 8.0% in subjects with type 1 diabetes and 1.1% in controls, aHR 9.05 (95% CI 7.18-11.41). In type 1 diabetes, male sex (aHR 1.45), higher age at onset of diabetes and lower education (higher compared to lower, aHR 0.38) were significantly associated with higher risk of AMI. There was no significant time trend in AMI by calendar year of diabetes onset.

CONCLUSIONS

We found nine-fold excess risk of AMI in subjects with type 1 diabetes, and three-fold higher risk in subjects with low versus high education. These results highlight a strengthened focus on prevention of cardiovascular disease, and diabetes education tailored to the subjects' educational background.

Worldwide estimates of incidence of type 2 diabetes in children and adolescents in 2021

AIMS

We aimed to conduct a systematic review of published studies on the incidence of type 2 diabetes in children and adolescents aged under 20 years and provide worldwide incidence estimates for 2021.

METHODS

We used MEDLINE and EMBASE to identify studies reporting type 2 diabetes incidence in children and adolescents published between Jan 2000 and April 2021. We used a negative binomial regression model to develop a prediction equation to estimate incidence rates from country characteristics. We applied the resulting incidence predictions to country population data to estimate numbers of incident cases in children and adolescents by International Diabetes Federation (IDF) region and World Bank income classification group.

RESULTS

We estimate that there are approximately 41,600 new cases of diagnosed type 2 diabetes among children and adolescents in 2021 worldwide. Around 30% and 40% of the worldwide total incident cases are in IDF Western Pacific region and in World Bank upper-middle-income countries, respectively. The three countries with the highest estimated number of incident cases are China, India, and United States of America.

CONCLUSIONS

The number of newly diagnosed type 2 diabetes in children and adolescents is substantial. More reliable data are needed to track the incidence of type 2 diabetes in children and adolescents.

Novel HNF1A gene mutation in maturity-onset diabetes of the young: A case report

BACKGROUND

Maturity-onset diabetes of the young 3 (MODY3), caused by mutations in the HNF1A gene, is the most common subtype of MODY. The diagnosis of MODY3 is critical because a low dose of sulfonylurea agents can achieve glucose control.

CASE SUMMARY

We describe a patient with MODY3 involving a novel splicing mutation, in whom low-dose gliclazide was sufficient to control clinically significant hyperglycemia. Sanger sequencing identified a splicing HNF1A mutation in 12q24 NM_000545.5 Intron5 c.1108-1G>A. Glycemic control has been maintained without insulin therapy for 28 mo after the diagnosis of diabetes.

CONCLUSION

This case report highlights a novel HNF1A gene mutation in MODY3 that is responsive to sulfonylurea therapy.

Next- generation sequencing is an effective method for diagnosing patients with different forms of monogenic diabetes

AIM

Monogenic diabetes (MD) represents 5-7% of antibody-negative diabetes cases and is a heterogeneous group of disorders.

METHODS

We used targeted next-generation sequencing (NGS) on Illumina NextSeq 550 platform involving the SureSelect assay to perform genetic and clinical characteristics of a study group of 684 individuals, including 542 patients referred from 12 Polish Diabetes Centers with suspected MD diagnosed between December 2016 and December 2019 and their 142 family members (FM).

RESULTS

In 198 probands (36.5%) and 66 FM (46.5%) heterozygous causative variants were confirmed in 11 different MD-related genes, including 31 novel mutations, with the highest number in the GCK gene (206/264), 22/264 in the HNF1A gene and 8/264 in the KCNJ11 gene. Of the 183 probands with MODY1-5 diabetes, 48.6% of them were diagnosed at the pre-diabetes stage and most of them (68.7%) were on diet only at the time of genetic diagnosis, while 31.3% were additionally treated with oral hypoglycaemic drugs and/or insulin.

CONCLUSIONS

In summary, the results obtained confirm the efficacy of targeted NGS method in the molecular diagnosis of patients with suspected MD and broaden the spectrum of new causal variants, while updating our knowledge of the clinical features of patients defined as having MD.

Diabetes Mellitus Diagnosed in Childhood and Adolescence With Negative Autoimmunity: Results of Genetic Investigation

Monogenic diabetes is a rare form of diabetes, accounting for approximately 1% to 6% of pediatric diabetes patients. Some types of monogenic diabetes can be misdiagnosed as type 1 diabetes in children or adolescents because of similar clinical features. Identification of the correct etiology of diabetes is crucial for clinical, therapeutic, and prognostic issues. Our main objective was to determine the prevalence of monogenic diabetes in patients with diabetes mellitus, diagnosed in childhood or in adolescence, and negative autoimmunity. We retrospectively analyzed clinical data of 275 patients diagnosed with insulin-dependent diabetes at age <18yr in the last 10 years. 8.4% of subjects has negative autoimmunity. Their DNA was sequenced by NGS custom panel composed by 45 candidate genes involved in glucose metabolism disorder. Two novel heterozygous pathogenic or likely pathogenic variants (10,5% of autoantibody negative subjects) were detected: the frameshift variant c.617_618insA in NEUROD1 exon 2 and the missense change c.116T>C in INS exon 2. Our study corroborates previous results of other reports in literature. NGS assays are useful methods for a correct diagnosis of monogenic diabetes, even of rarest forms, highlighting mechanisms of pediatric diabetes pathogenesis.

Relation of Health-Related Quality of Life with Glycemic Control and Use of Diabetes Technology in Children and Adolescents with Type 1 Diabetes: Results from a National Population Based Study

OBJECTIVE

The primary aim was to analyse the association between diabetes-specific health-related quality of life (HRQOL) and HbA1c in children and adolescents with type 1 diabetes. The secondary aims were to evaluate the associations between diabetes-specific HRQOL and age, sex, diabetes duration, and the use of diabetes technology in diabetes treatment. Research Design and Methods. Children with type 1 diabetes (10-17 years, N = 1,019) and parents (children <10 years, N = 371; 10-17 years, N = 1,070) completed the DISABKIDS diabetes-specific questionnaire (DDM-10) as part of the 2017 data collection for the Norwegian Childhood Diabetes Registry. The DDM-10 consists of two subscales-'impact' and 'treatment'-with six and four items, respectively. In the linear regression models, the items and subscales were outcome variables, while HbA1c, age, sex, diabetes duration, insulin pump use, and continuous glucose monitoring (CGM) system use were predictor variables.

RESULTS

Lower HbA1c measurements and male sex were associated with higher HRQOL scores on both DDM-10 scales in the age group 10-17 years, but not in children under 10 years. Parents gave lower HRQOL scores than children in the 10-17 age group. Insulin pump and CGM use were not significantly associated with HRQOL on the impact and treatment scale.

CONCLUSIONS

Low HbA1c and male sex are significantly associated with high HRQOL in children aged 10-17 with type 1 diabetes, but the use of diabetes technology is not positively associated with HRQOL. Differences in child- and parent-reported scores imply that parents might both over- and underestimate their child's HRQOL.

Investigating the association between prenatal exposure to folic acid and risk of neonatal diabetes/hyperglycemia and type 1 diabetes: A Norwegian register-based study

BACKGROUND

Experimental animal studies suggest a novel role for the folate receptor 1 in β-cell differentiation in the pancreas, with potential implications for glycemic control. We tested the hypothesis of a protective association between prenatal folic acid use and neonatal diabetes or hyperglycemia and type 1 diabetes in an observational cohort study using data from the national population health registers in Norway.

METHODS

All singleton pregnancies resulting in live births from 2005 to 2018 were identified. Prenatal exposure to folic acid was determined based on maternal report at antenatal care in early pregnancy. Diagnoses of neonatal diabetes, hyperglycemia, and type 1 diabetes for the children were identified. Associations were estimated with logistic regression or Cox proportional hazard model and included crude and adjusted estimates.

RESULTS

Among 781,567 children, 69% had prenatal exposure to folic acid, 264 were diagnosed with neonatal diabetes or hyperglycemia, and 1390 with type 1 diabetes. Compared to children with no prenatal exposure to folic acid, children with prenatal exposure to folic acid had similar odds of having a neonatal diabetes or hyperglycemia diagnosis (adjusted odds ratio 0.95, 95% confidence interval [CI] 0.72, 1.25) and similar risk of being diagnosed with type 1 diabetes (adjusted hazard ratio 1.05, 95% CI 0.93, 1.18).

CONCLUSIONS

No association between prenatal folic acid exposure and neonatal diabetes/hyperglycemia or type 1 diabetes was found. These findings do not rule out a translational effect of the experimental results and future studies with longer follow-up and more precise information on the window of prenatal exposure are needed.

Why all MODY variants are dominantly inherited: a hypothesis

Maturity-onset diabetes in the young (MODY) comprises monogenic phenotypes of young-onset, insulinopenic diabetes. All its forms are dominantly inherited. Why? Are the pancreatic β cells only harmed by heterozygous variants? We propose that recessive MODYs do exist but have escaped detection due to lack of family history suggestive of monogenic inheritance.

Maturity Onset Diabetes of the Young-New Approaches for Disease Modelling

Maturity-onset diabetes of the young (MODY) is a genetically heterogeneous group of monogenic endocrine disorders that is characterised by autosomal dominant inheritance and pancreatic β-cell dysfunction. These patients are commonly misdiagnosed with type 1 or type 2 diabetes, as the clinical symptoms largely overlap. Even though several biomarkers have been tested none of which could be used as single clinical discriminator. The correct diagnosis for individuals with MODY is of utmost importance, as the applied treatment depends on the gene mutation or is subtype-specific. Moreover, in patients with HNF1A-MODY, additional clinical monitoring can be included due to the high incidence of vascular complications observed in these patients. Finally, stratification of MODY patients will enable better and newer treatment options for MODY patients, once the disease pathology for each patient group is better understood. In the current review the clinical characteristics and the known disease-related abnormalities of the most common MODY subtypes are discussed, together with the up-to-date applied diagnostic criteria and treatment options. Additionally, the usage of pluripotent stem cells together with CRISPR/Cas9 gene editing for disease modelling with the possibility to reveal new pathophysiological mechanisms in MODY is discussed.

A new screening strategy and whole-exome sequencing for the early diagnosis of maturity-onset diabetes of the young

AIMS

This study aimed to establish a systematic screening strategy to select candidates for genetic testing among patients with maturity-onset diabetes of the young (MODY) and to accomplish early diagnosis of MODY.

MATERIALS AND METHODS

We enrolled 1478 sporadic patients from the outpatient department of endocrinology. Out of the1478 patients, 1279 participants were successfully screened according to the "AACM" strategy, which includes the age of onset, autoantibody to islet antigen, C-peptide and metabolic syndrome. Another six probands and their families who fulfilled the common clinical criteria for MODY were also examined for causative gene mutations. Whole-exome sequencing (WES) was performed to examine the mutations.

RESULTS

A total of 24 out of 1279 sporadic patients with newly diagnosed diabetes were eligible for genetic testing. Mutations were found in 4/24 participants in the cohort, as well as in 2/6 pedigrees. A likely pathogenic alteration, a likely benign alteration and three alterations with uncertain significance were identified with WES. Most of the mutant genes recognised in our trial were not the most common causative genes of MODY, and all of the mutations were specifically reported in Asian patients only, suggesting a unique genetic background of MODY in different ethnicities.

CONCLUSIONS

In this systematic study of MODY in a new-onset diabetes cohort, MODY cases were incorrectly diagnosed as type 1 diabetes mellitus (T1DM) and type 2 diabetes mellitus (T2DM), suggesting that an observant clinician is necessary for early and correct MODY diagnosis. This systematic approach to screening is practical and specific enough to identify patients who are most appropriate for genetic testing.

Genetic Spectrum of Neonatal Diabetes

Neonatal diabetes (ND) appears during the first months of life and is caused by a single gene mutation. It is heterogenous and very different compared to other forms of multi-factorial or polygenic diabetes. Clinically, this form is extremely severe, however, early genetic diagnosis is pivotal for successful therapy. A large palette of genes is demonstrated to be a cause of ND, however, the mechanisms of permanent hyperglycemia are different. This review will give an overview of more frequent genetic mutations causing ND, including the function of the mutated genes and the specific therapy for certain sub-forms.

Etiologic distribution and clinical characteristics of pediatric diabetes in 276 children and adolescents with diabetes at a single academic center

Background

The prevalence of monogenic diabetes is estimated to be 1.1–6.3% of patients with diabetes mellitus (DM) in Europe. The overlapping clinical features of various forms of diabetes make differential diagnosis challenging. Therefore, this study investigated the etiologic distribution and clinical characteristics of pediatric diabetes, including monogenic diabetes, who presented at a single tertiary center over the last 20 years.

Methods

This study included 276 consecutive patients with DM diagnosed before 18 years of age from January 2000 to December 2019 in Korea. Clinical features, biochemical findings, β-cell autoantibodies, and molecular characteristics were reviewed retrospectively.

Results

Of the 276 patients, 206 patients (74.6%), 49 patients (17.8%), and 21 patients (7.6%) were diagnosed with type 1 DM, type 2 DM, and clinically suspected monogenic diabetes, respectively. Among 21 patients suspected to have monogenic diabetes, 8 patients had clinical maturity-onset diabetes of the young (MODY), and the remaining 13 patients had other types of monogenic diabetes. Among them, genetic etiologies were identified in 14 patients (5.1%) from 13 families, which included MODY 5, transient neonatal DM, developmental delay, epilepsy, and neonatal diabetes (DEND) syndrome, Wolfram syndrome, Donohue syndrome, immune dysregulation, polyendocrinopathy, enteropathy, X-linked (IPEX) syndrome, Fanconi-Bickel syndrome, Wolcott-Rallison syndrome, cystic fibrosis-related diabetes, and maternally inherited diabetes and deafness.

Conclusions

Genetically confirmed monogenic diabetes accounted for 5.1% of patients evaluated at a single tertiary center over 20-year period. Based on the findings for our sample, the frequency of mutations in the major genes of MODY appears to be low among pediatric patients in Korea. It is critical to identify the genetic cause of DM to provide appropriate therapeutic options and genetic counseling.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12887-021-02575-6.

Clinical features, complications and treatment of rarer forms of maturity-onset diabetes of the young (MODY) - A review

Maturity onset diabetes of the young (MODY) is the most common form of monogenic diabetes and is currently believed to have 14 subtypes. While much is known about the common subtypes of MODY (MODY-1, 2, 3 and 5) little is known about its rare subtypes (MODY4, 6-14). With the advent of next-generation sequencing (NGS) there are several reports of the rarer subtypes of MODY emerging from across the world. Therefore, a greater understanding on these rarer subtypes is needed. A search strategy was created, and common databases were searched, and 51 articles finally selected. INS-(MODY10) and ABCC8-(MODY12) mutations were reported in relatively large numbers compared to the other rare subtypes. The clinical characteristics of the rare MODY subtypes exhibited heterogeneity between families reported with the same mutation. Obesity and diabetic ketoacidosis (DKA) were also reported among rarer MODY subtypes which presents as a challenge as these are not part of the original description of MODY by Tattersal and Fajans. The treatment modalities of the rarer subtypes included oral drugs, predominantly sulfonylureas, insulin but also diet alone. Newer drugs like DPP-4 and SGLT2 inhibitors have also been tried as new modes of treatment. The microvascular and macrovascular complications among the patients with various MODY subtypes are less commonly reported. Recently, there is a view that not all the 14 forms of 'MODY' are true MODY and the very existence of some of these rarer subtypes as MODY has been questioned. This scoping review aims to report on the clinical characteristics, treatment and complications of the rarer MODY subtypes published in the literature.

Identification of Novel GCK and HNF4α Gene Variants in Japanese Pediatric Patients with Onset of Diabetes before 17 Years of Age

BACKGROUND

Maturity-onset diabetes of the young (MODY) is commonly misdiagnosed as type 1 or type 2 diabetes. Common reasons for misdiagnosis are related to limitations in genetic testing. A precise molecular diagnosis is essential for the optimal treatment of patients and allows for early diagnosis of their asymptomatic family members.

OBJECTIVE

The aim of this study was to identify rare monogenic variants of common MODY genes in Japanese pediatric patients.

METHODS

We investigated 45 Japanese pediatric patients based on the following clinical criteria: development of diabetes before 17 years of age, a family history of diabetes, testing negative for glutamate decarboxylase-65 (GAD 65) antibodies and insulinoma-2-associated autoantibodies (IA-2A), no significant obesity, and evidence of endogenous insulin production. Genetic screening for MODY1 (HNF4α), MODY2 (GCK), MODY3 (HNF1α), and MODY5 (HNF1β) was performed by direct sequencing followed by multiplex ligation amplification assays.

RESULTS

We identified 22 missense variants (3 novel variants) in 27 patients (60.0%) in the GCK, HNF4α, and HNF1α genes. We also detected a whole exon deletion in the HNF1β gene and an exon 5-6 aberration in the GCK gene, each in one proband (4.4%). There were a total of 29 variations (64.4%), giving a relative frequency of 53.3% (24/45) for GCK, 2.2% (1/45) for HNF4α, 6.7% (3/45) for HNF1α, and 2.2% (1/45) for HNF1β genes.

CONCLUSIONS

Clinicians should consider collecting and assessing detailed clinical information, especially regarding GCK gene variants, in young antibody-negative patients with diabetes. Correct molecular diagnosis of MODY better predicts the clinical course of diabetes and facilitates individualized management.

The epidemiology, molecular pathogenesis, diagnosis, and treatment of maturity-onset diabetes of the young (MODY)

Background

The most common type of monogenic diabetes is maturity-onset diabetes of the young (MODY), a clinically and genetically heterogeneous group of endocrine disorders that affect 1–5% of all patients with diabetes mellitus. MODY is characterized by autosomal dominant inheritance but de novo mutations have been reported. Clinical features of MODY include young-onset hyperglycemia, evidence of residual pancreatic function, and lack of beta cell autoimmunity or insulin resistance. Glucose-lowering medications are the main treatment options for MODY. The growing recognition of the clinical and public health significance of MODY by clinicians, researchers, and governments may lead to improved screening and diagnostic practices. Consequently, this review article aims to discuss the epidemiology, pathogenesis, diagnosis, and treatment of MODY based on relevant literature published from 1975 to 2020.

Main body

The estimated prevalence of MODY from European cohorts is 1 per 10,000 in adults and 1 per 23,000 in children. Since little is known about the prevalence of MODY in African, Asian, South American, and Middle Eastern populations, further research in non-European cohorts is needed to help elucidate MODY’s exact prevalence. Currently, 14 distinct subtypes of MODY can be diagnosed through clinical assessment and genetic analysis. Various genetic mutations and disease mechanisms contribute to the pathogenesis of MODY. Management of MODY is subtype-specific and includes diet, oral antidiabetic drugs, or insulin.

Conclusions

Incidence and prevalence estimates for MODY are derived from epidemiologic studies of young people with diabetes who live in Europe, Australia, and North America. Mechanisms involved in the pathogenesis of MODY include defective transcriptional regulation, abnormal metabolic enzymes, protein misfolding, dysfunctional ion channels, or impaired signal transduction. Clinicians should understand the epidemiology and pathogenesis of MODY because such knowledge is crucial for accurate diagnosis, individualized patient management, and screening of family members.

Serum microRNA as indicators of Wolfram syndrome's progression in neuroimaging studies

INTRODUCTION

Patients with the ultra-rare Wolfram syndrome (WFS) develop insulin-dependent diabetes and progressive neurodegeneration. The aim of the study was to quantify microRNAs (miRNAs) in sera from patients with WFS, correlate their expression with neurological imaging over time and compare miRNA levels with those observed in patients with type 1 diabetes mellitus (T1DM).

RESEARCH DESIGN AND METHODS

We quantified miRNA expression (Qiagen, Germany) in two groups of patients: with WFS at study entry (n=14) and after 2 years of follow-up and in 15 glycated hemoglobin-matched (p=0.72) patients with T1DM.

RESULTS

We observed dynamic changes in the expression of multiple miRNAs in patients with WFS parallel to disease progression and in comparison to the T1DM patients group. Among miRNAs that differed between baseline and follow-up WFS samples, the level of 5 increased over time (miR-375, miR-30d-5p, miR-30e-30, miR-145-5p and miR-193a-5p) and was inversely correlated with macular average thickness, while the expression of 2 (let-7g-5p and miR-22-3p) decreased and was directly correlated with neuroimaging indicators of neurodegeneration.

CONCLUSIONS

Our findings show for the first time that serum miRNAs can be used as easily accessible indicators of disease progression in patients with WFS, potentially facilitating clinical trials on mitigating neurodegeneration.

Molecular Genetic Study in a Cohort of Iranian Families Suspected to Maturity-Onset Diabetes of the Young, Reveals a Recurrent Mutation and a High-Risk Variant in the CEL Gene

Background

Diabetes mellitus (DM) is a group of metabolic disorders in the body, accompanied with increasing blood sugar levels. Diabetes is classified into three groups: Type 1 DM (T1DM), Type 2 DM (T2DM), and monogenic diabetes. Maturity-onset diabetes of the young (MODY) is a monogenic diabetes that is frequently mistaken for T1D or T2D. The aim of this study was to diagnose MODY and its subtype frequency in a diabetic population in Iran.

Materials and Methods

In this study among ten diabetic families that were highly suspected to MODY by nongenetic biomarkers and without any pathogenic mutation in GCK and HNF1A genes, two patients from two unrelated families were examined via whole-exome sequencing (WES) in order to detect the causative gene of diabetes. Co-segregation analysis of the identified variant was performed using Sanger sequencing.

Results

In this study, no pathogenic variant was found in GCK and HNF1A genes (MODY2 and MODY3), while these two types of MODY were introduced as the most frequent in other studies. By using WES, a pathogenic variant (p.I488T) was found in one of the patients in CEL gene causing MODY8 that its frequency is very rare in other studied populations. A high-risk variant associated with diabetes was found in another patient.

Conclusion

WES was applied in this study to reveal the cause of MODY in 1 family. This pathogenic mutation was previously reported as a disease causing mutation.

A novel gene in early childhood diabetes: EDEM2 silencing decreases SLC2A2 and PXD1 expression, leading to impaired insulin secretion

Monogenic diabetes is a rare type of diabetes resulting from mutations in a single gene. To date, most cases remain genetically unexplained, posing a challenge for accurate diabetes treatment, which leads to on a molecular diagnosis. Therefore, a trio exome scan was performed in a lean, nonsyndromic Caucasian girl with diabetes onset at 2½ years who was negative for autoantibodies. The lean father had diabetes from age 11 years. A novel heterozygous mutation in EDEM2, c.1271G > A; p.Arg424His, was found in the proband and father. Downregulation of Edem2 in rat RIN-m β-cells resulted in a decrease in insulin genes Ins1 to 67.9% (p = 0.006) and Ins2 to 16.8% (p < 0.001) and reduced insulin secretion by 60.4% (p = 0.0003). Real-time PCR revealed a major disruption of endocrine pancreas-specific genes, including Glut2 and Pxd1, with mRNA suppression to 54% (p < 0.001) and 85.7% (p = 0.01), respectively. No other expression changes related to stress or apoptotic genes were observed. Extended clinical follow-up involving ten family members showed that two healthy individuals carried the same mutation with no sign of diabetes in the clinical screen except for a slight increase in IA-2 antibody in one of them, suggesting incomplete penetrance. In conclusion, we describe EDEM2 as a likely/potential novel diabetes gene, in which inhibition in vitro reduces the expression of β-cell genes involved in the glucose-stimulated insulin secretion (GSIS) pathway, leading to an overall suppression of insulin secretion but not apoptosis.

Beta cell function and insulin sensitivity in obese youth with maturity onset diabetes of youth mutations vs type 2 diabetes in TODAY: Longitudinal observations and glycemic failure

OBJECTIVE

In treatment options for type 2 diabetes in adolescents and youth (TODAY), 4.5% of obese youth clinically diagnosed with type 2 diabetes (T2D) had genetic variants consistent with maturity onset diabetes of youth (MODY) diagnosis. The course of IS and β-cell function in obese youth with MODY remains unknown. In this secondary analysis, we examined IS and β-cell function in MODY vs. non-MODY obese youth at randomization and over time.

METHODS

Genetic data in TODAY included 426 non-MODY (T2D) and 22 MODY youth (7 glucokinase MODY mutation positive [GCK-MODY], 12 hepatocyte nuclear factor MODY mutation positive [HNF-MODY], 2 Insulin gene mutation [insulin (INS)-MODY], and 1 Kruppel-like factor 11 [KLF11-MODY]). Oral glucose tolerance test (OGTT)-derived IS, C-peptide index, and β-cell function relative to IS oral disposition index (oDI) was measured at randomization, and over 24 months in addition to total and high-molecular-weight adiponectin (HMWA).

RESULTS

At randomization, IS, total adiponectin, and HMWA were significantly higher in the two MODY groups than in non-MODY. β-cell function measured by C-peptide oDI was 3-fold higher in GCK-MODY than in HNF-MODY and 1.5-fold higher than non-MODY (P for both <.05). Glycemic failure rate was 75.0% in HNF-MODY, 46.9% in non-MODY, and zero in GCK-MODY youth. While the changes in IS and oDI were not different among the three groups in the first 6 months, IS improved from 6 to 24 months in HNF-MODY vs GCK-MODY youth.

CONCLUSIONS

In TODAY, β-cell function at randomization was worse in obese HNF-MODY youth compared with GCK-MODY youth, while insulin sensitivity was worse in non-MODY compared with the other two MODY groups. Over time, IS showed the greatest improvement in HNF-MODY youth. This raises the possibility that TODAY therapeutic modalities of insulin sensitization in these obese HNF-MODY youth may have played a beneficial role.

Genetics and Pathophysiology of Maturity-onset Diabetes of the Young (MODY): A Review of Current Trends

Single gene mutations have been implicated in the pathogenesis of a form of diabetes mellitus (DM) known as the maturity-onset diabetes of the young (MODY). However, there are diverse opinions on the suspect genes and pathophysiology, necessitating the need to review and communicate the genes to raise public awareness. We used the Google search engine to retrieve relevant information from reputable sources such as PubMed and Google Scholar. We identified 14 classified MODY genes as well as three new and unclassified genes linked with MODY. These genes are fundamentally embedded in the beta cells, the most common of which are HNF1A, HNF4A, HNF1B, and GCK genes. Mutations in these genes cause β-cell dysfunction, resulting in decreased insulin production and hyperglycemia. MODY genes have distinct mechanisms of action and phenotypic presentations compared with type 1 and type 2 DM and other forms of DM. Healthcare professionals are therefore advised to formulate drugs and treatment based on the causal genes rather than the current generalized treatment for all types of DM. This will increase the effectiveness of diabetes drugs and treatment and reduce the burden of the disease.

Systematic Genetic Study of Youth With Diabetes in a Single Country Reveals the Prevalence of Diabetes Subtypes, Novel Candidate Genes, and Response to Precision Therapy

Identifying gene variants causing monogenic diabetes (MD) increases understanding of disease etiology and allows for implementation of precision therapy to improve metabolic control and quality of life. Here, we aimed to assess the prevalence of MD in youth with diabetes in Lithuania, uncover potential diabetes-related gene variants, and prospectively introduce precision treatment. First, we assessed all pediatric and most young-adult patients with diabetes in Lithuania (n = 1,209) for diabetes-related autoimmune antibodies. We then screened all antibody-negative patients (n = 153) using targeted high-throughput sequencing of >300 potential candidate genes. In this group, 40.7% had MD, with the highest percentage (100%) in infants (diagnosis at ages 0-12 months), followed by those diagnosed at ages >1-18 years (40.3%) and >18-25 years (22.2%). The overall prevalence of MD in youth with diabetes in Lithuania was 3.5% (1.9% for GCK diabetes, 0.7% for HNF1A, 0.2% for HNF4A and ABCC8, 0.3% for KCNJ11, and 0.1% for INS). Furthermore, we identified likely pathogenic variants in 11 additional genes. Microvascular complications were present in 26% of those with MD. Prospective treatment change was successful in >50% of eligible candidates, with C-peptide >252 pmol/L emerging as the best prognostic factor.

High Prevalence of a Monogenic Cause in Han Chinese Diagnosed With Type 1 Diabetes, Partly Driven by Nonsyndromic Recessive WFS1 Mutations

It is estimated that ∼1% of European ancestry patients clinically diagnosed with type 1 diabetes (T1D) actually have monogenic forms of the disease. Because of the much lower incidence of true T1D in East Asians, we hypothesized that the percentage would be much higher. To test this, we sequenced the exome of 82 Chinese Han patients clinically diagnosed with T1D but negative for three autoantibodies. Analysis focused on established or proposed monogenic diabetes genes. We found credible mutations in 18 of the 82 autoantibody-negative patients (22%). All mutations had consensus pathogenicity support by five algorithms. As in Europeans, the most common gene was HNF1A (MODY3), in 6 of 18 cases. Surprisingly, almost as frequent were diallelic mutations in WFS1, known to cause Wolfram syndrome but also described in nonsyndromic cases. Fasting C-peptide varied widely and was not predictive. Given the 27.4% autoantibody negativity in Chinese and 22% mutation rate, we estimate that ∼6% of Chinese with a clinical T1D diagnosis have monogenic diabetes. Our findings support universal sequencing of autoantibody-negative cases as standard of care in East Asian patients with a clinical T1D diagnosis. Nonsyndromic diabetes with WSF1 mutations is not rare in Chinese. Its response to alternative treatments should be investigated.

Genetic characterization of suspected MODY patients in Tunisia by targeted next-generation sequencing

AIMS

Maturity Onset Diabetes of the Young (MODY) is a monogenic form of diabetes with autosomal dominant inheritance pattern. The diagnosis of MODY and its subtypes is based on genetic testing. Our aim was investigating MODY by means of next-generation sequencing in the Tunisian population.

METHODS

We performed a targeted sequencing of 27 genes known to cause monogenic diabetes in 11 phenotypically suspected Tunisian patients. We retained genetic variants passing filters of frequency in public databases as well as their probable effects on protein structures and functions evaluated by bioinformatics prediction tools.

RESULTS

Five heterozygous variants were found in four patients. They include two mutations in HNF1A and GCK that are the causative genes of the two most prevalent MODY subtypes described in the literature. Other possible mutations, including novel frameshift and splice-site variants were identified in ABCC8 gene.

CONCLUSIONS

Our study is the first to investigate the clinical application of targeted next-generation sequencing for the diagnosis of MODY in Africa. The combination of this approach with a filtering/prioritization strategy made a step towards the identification of MODY mutations in the Tunisian population.

GCK-MODY in the US Monogenic Diabetes Registry: Description of 27 unpublished variants

We report on 134 unique GCK variants in 217 families, including 27 unpublished variants, identified in the US Monogenic Diabetes Registry in the last decade. Using ACMG guidelines, 26% were pathogenic, 56% likely pathogenic and 18% were of uncertain significance. Those with pathogenic variants had clinical features consistent with GCK-MODY.

Identifying Pathogenic Variants of Monogenic Diabetes Using Targeted Panel Sequencing in an East Asian Population

PURPOSE

Monogenic diabetes is a specific type of diabetes in which precision medicine could be applied. In this study, we used targeted panel sequencing to investigate pathogenic variants in Korean patients clinically suspected to have monogenic diabetes.

METHODS

The eligibility criteria for inclusion were non-type 1 diabetes patients with an age of onset ≤ 30 years and a BMI (body mass index) ≤ 30 kg/m2. Among the 2,090 non-type 1 diabetes patients, 109 were suspected to have monogenic diabetes and subjected to genetic testing. We analyzed 30 monogenic diabetes genes using targeted panel sequencing. The pathogenicity of the genetic variants was evaluated according to the American College of Medical Genetics and Genomics and the Association for Molecular Pathology guidelines.

RESULTS

Among the 109 suspected monogenic diabetes patients, 23 (21.1%) patients harbored pathogenic/likely pathogenic variants. A total of 14 pathogenic/likely pathogenic variants of common maturity onset diabetes of the young (MODY) genes were identified in GCK, HNF1A, HNF4A, and HNF1B. Other pathogenic/likely pathogenic variants were identified in WFS1, INS, ABCC8 and FOXP3. The mitochondrial DNA 3243 A>G variant was identified in five participants. Patients with pathogenic/likely pathogenic variants had a significantly higher MODY probability, a lower BMI, and a lower C-peptide level than those without pathogenic/likely pathogenic variants (P=0.007, P=0.001, and P=0.012, respectively).

CONCLUSIONS

Using targeted panel sequencing followed by pathogenicity evaluation, we were able to make molecular genetic diagnoses for 23 (21.1%) suspected monogenic diabetes patients. Lower BMI, higher MODY probability, and lower C-peptide levels were characteristics of these participants.

Frequency and Characteristics of MODY 1 (HNF4A Mutation) and MODY 5 (HNF1B Mutation): Analysis From the DPV Database

OBJECTIVE

To characterize the initial presentation and clinical course of patients with hepatocyte nuclear factor (HNF) 4A‒ and HNF1B‒MODY in a multinational registry.

DESIGN, SETTING, AND PARTICIPANTS

Within the Diabetes Patienten Verlaufsdokumentation (DPV) registry, 44 patients with HNF4A- and 35 patients with HNF1B-MODY were characterized and compared with patients <20 years old with type 1 diabetes (T1D)/type 2 diabetes (T2D).

MAIN OUTCOME MEASURE

Clinical and laboratory parameters, therapy, metabolic control, and extrapancreatic symptoms in patients with HNF1B-MODY.

RESULTS

Patients with both MODY types were significantly older than patients with T1D at diagnosis (HNF4A, 13.8 years, and HNF1B, 13.5 years, vs T1D, 8.8 years; P < 0.0001). Mean C-peptide at diagnosis was higher for HNF4A-MODY than for T1D (1.8 vs 0.9 ng/mL; P < 0.01); 36.4% of patients with HNF4A-MODY and 65.7% of patients with HNF1B-MODY were treated with insulin, whereas 20.5% and 8.6% received oral antidiabetics only (P < 0.05 and P < 0.01 vs T2D). At the most recent visit, glycated hemoglobin levels were lower in HNF4A- and HNF1B-MODY (mean, 6.5% and 6.1%) than in T1D (7.9%; P < 0.0001). In 40% of patients with HNF1B-MODY, extrapancreatic symptoms were reported. Several clinical predictors previously described to differentiate between MODY and T1D or T2D were revalidated by logistic regression analyses in this cohort.

CONCLUSION

The DPV registry enabled us to precisely characterize phenotype and treatment in these two rare MODY types. Although phenotype of HNF4A- and HNF1B-MODY showed distinct differences from those of T1D and T2D, 38% of patients were initially misclassified as having T1D or T2D.

Comprehensive genetic screening: The prevalence of maturity-onset diabetes of the young gene variants in a population-based childhood diabetes cohort

BACKGROUND

Maturity-onset diabetes of the young (MODY) is caused by autosomal dominant mutations in one of 13 confirmed genes. Estimates of MODY prevalence vary widely, as genetic screening is usually restricted based on clinical features, even in population studies. We aimed to determine prevalence of MODY variants in a large and unselected pediatric diabetes cohort.

METHODS

MODY variants were assessed using massively parallel sequencing in the population-based diabetes cohort (n = 1363) of the sole tertiary pediatric diabetes service for Western Australia (population 2.6 million). All individuals were screened, irrespective of clinical features. MODY variants were also assessed in a control cohort (n = 993).

RESULTS

DNA and signed consent were available for 821 children. Seventeen children had pathogenic/likely pathogenic variants in MODY genes, two diagnosed with type 2 diabetes, four diagnosed with antibody-negative type 1 diabetes (T1DM), three diagnosed with antibody-positive T1DM, and eight previously diagnosed with MODY. Prevalence of MODY variants in the sequenced cohort was 2.1%, compared to 0.3% of controls.

CONCLUSIONS

This is the first comprehensive study of MODY variants in an unselected population-based pediatric diabetes cohort. The observed prevalence, increasing access to rapid and affordable genetic screening, and significant clinical implications suggest that genetic screening for MODY could be considered for all children with diabetes, irrespective of other clinical features.

Monogenic Forms of Diabetes Mellitus

In addition to the common types of diabetes mellitus, two major monogenic diabetes forms exist. Maturity-onset diabetes of the young (MODY) represents a heterogenous group of monogenic, autosomal dominant diseases. MODY accounts for 1-2% of all diabetes cases, and it is not just underdiagnosed but often misdiagnosed to type 1 or type 2 diabetes. More than a dozen MODY genes have been identified to date, and their molecular classification is of great importance in the correct treatment decision and in the judgment of the prognosis. The most prevalent subtypes are HNF1A, GCK, and HNF4A. Genetic testing for MODY has changed recently due to the technological advancements, as contrary to the sequential testing performed in the past, nowadays all MODY genes can be tested simultaneously by next-generation sequencing. The other major group of monogenic diabetes is neonatal diabetes mellitus which can be transient or permanent, and often the diabetes is a part of a syndrome. It is a severe monogenic disease appearing in the first 6 months of life. The hyperglycemia usually requires insulin. There are two forms, permanent neonatal diabetes mellitus (PNDM) and transient neonatal diabetes mellitus (TNDM). In TNDM, the diabetes usually reverts within several months but might relapse later in life. The incidence of NDM is 1:100,000-1:400,000 live births, and PNDM accounts for half of the cases. Most commonly, neonatal diabetes is caused by mutations in KCNJ11 and ABCC8 genes encoding the ATP-dependent potassium channel of the β cell. Neonatal diabetes has experienced a quick and successful transition into the clinical practice since the discovery of the molecular background. In case of both genetic diabetes groups, recent guidelines recommend genetic testing.

A UK nationwide prospective study of treatment change in MODY: genetic subtype and clinical characteristics predict optimal glycaemic control after discontinuing insulin and metformin

AIMS/HYPOTHESIS

Treatment change following a genetic diagnosis of MODY is frequently indicated, but little is known about the factors predicting future treatment success. We therefore conducted the first prospective study to determine the impact of a genetic diagnosis on individuals with GCK-, HNF1A- or HNF4A-MODY in the UK, and to identify clinical characteristics predicting treatment success (i.e. HbA_1c ≤58 mmol/mol [≤7.5%]) with the recommended treatment at 2 years.

METHODS

This was an observational, prospective, non-selective study of individuals referred to the Exeter Molecular Genetic Laboratory for genetic testing from December 2010 to December 2012. Individuals from the UK with GCK- or HNF1A/HNF4A-MODY who were not on recommended treatment at the time of genetic diagnosis, and who were diagnosed below the age of 30 years and were currently aged less than 50 years, were eligible to participate.

RESULTS

A total of 44 of 58 individuals (75.9%) changed treatment following their genetic diagnosis. Eight individuals diagnosed with GCK-MODY stopped all diabetes medication without experiencing any change in HbA_1c (49.5 mmol/mol [6.6%] both before the genetic diagnosis and at a median of 1.25 years' follow-up without treatment, p = 0.88). A total of 36 of 49 individuals (73.5%) diagnosed with HNF1A/HNF4A-MODY changed treatment; however, of the 21 of these individuals who were being managed with diet or sulfonylurea alone at 2 years, only 13 (36.1% of the population that changed treatment) had an HbA_1c ≤58 mmol/mol (≤7.5%). These individuals had a shorter diabetes duration (median 4.6 vs 18.1 years), lower HbA_1c (58 vs 73 mmol/mol [7.5% vs 8.8%]) and lower BMI (median 24.2 vs 26.0 kg/m²) at the time of genetic diagnosis, compared with individuals (n = 23/36) with an HbA_1c >58 mmol/mol (>7.5%) (or <58 mmol/mol [<7.5%] on additional treatment) at the 2 year follow-up. Overall, 64% (7/11) individuals with a diabetes duration of ≤11 years and an HbA_1c of ≤69 mmol/mol (≤8.5%) at time of the genetic test achieved good glycaemic control (HbA_1c ≤58 mmol/mol [≤7.5%]) with diet or sulfonylurea alone at 2 years, compared with no participants with a diabetes duration of >11 years and an HbA_1c of >69 mmol/mol (>8.5%) at the time of genetic diagnosis.

CONCLUSIONS/INTERPRETATION

In participants with GCK-MODY, treatment cessation was universally successful, with no change in HbA_1c at follow-up. In those with HNF1A/HNF4A-MODY, a shorter diabetes duration, lower HbA_1c and lower BMI at genetic diagnosis predicted successful treatment with sulfonylurea/diet alone, supporting the need for early genetic diagnosis and treatment change. Our study suggests that, in individuals with HNF1A/HNF4A-MODY with a longer duration of diabetes (>11 years) at time of genetic test, rather than ceasing current treatment, a sulfonylurea should be added to existing therapy, particularly in those who are overweight or obese and have a high HbA_1c.

Antibiotics, acetaminophen and infections during prenatal and early life in relation to type 1 diabetes

Background

Infections in early life have been linked to type 1 diabetes (T1D) risk, but no previous study has comprehensively analysed exposure to antibiotics, acetaminophen and infections during pregnancy and early childhood in relation to offspring risk of T1D.

Methods

Participants in the Norwegian Mother and Child Cohort Study (n = 114 215 children, of whom 403 children were diagnosed with T1D) reported infections and medication use through repeated questionnaires from pregnancy until the children were 18 months old. Adjusted hazard ratios (aHR) for offspring T1D were estimated through Cox regression adjusted for child's sex, maternal age and parity, maternal T1D, smoking in pregnancy, education level, pre-pregnancy body mass index (BMI) and birthweight. Antibiotic use was also analysed in a population-based register cohort of 541 036 children of whom 836 developed T1D.

Results

Hospitalization for gastroenteritis during the first 18 months of life was associated with increased risk (aHR 2.27, 95% CI 1.21 - 4.29, P = 0.01) of T1D. Childhood infections not requiring hospitalization, or any kind of maternal infection during pregnancy, did not predict offspring risk of T1D. Antibiotic or acetaminophen use in pregnancy, or child`s use in early childhood, was not associated with risk of T1D.

Conclusions

Our study, which is population-based and the largest of its kind, did not find support for general early life infections, infection frequency or use of antibiotics or acetaminophen to play a major role in childhood T1D. Hospital admission for gastroenteritis was associated with T1D risk, but must be interpreted cautiously due to scarcity of cases.

COL4A3 Gene Variants and Diabetic Kidney Disease in MODY

BACKGROUND AND OBJECTIVES

Despite advances in identifying genetic factors of diabetic kidney disease (DKD), much of the heritability remains unexplained. Nine maturity-onset diabetes in young (MODY) probands with kidney biopsy-proven DKD were selected and included in this study. The probands had more severe DKD compared with their parents with MODY, with overt proteinuria or rapid progression to ESKD. We aimed to explore the contribution of the variants in susceptibility genes of DKD to the severity of kidney phenotype between the probands and their parents.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Whole-exome sequencing was performed to identify suspected MODY probands and their families. Known DKD susceptibility genes were reviewed. Variants reported to be associated with DKD, or those with minor allele frequency <0.05 and predicted to be pathogenic, were selected and analyzed. Immunofluorescence staining of COL4α3 was performed in kidney specimens of patients with DKD with or without R408H and M1209I of COL4A3 variants.

RESULTS

HNF1B-MODY, CEL-MODY, PAX4-MODY, and WFS1-MODY were diagnosed among nine families. We identified 196 selected variants of 25 DKD susceptibility genes among the participants. Analysis of phenotype between probands and parents, gene function, and protein-protein interaction networks revealed that COL4A3 variants were involved in the progression of DKD. Weak granular staining of COL4α3 was observed in the glomerular basement membrane of patients with the R408H and M1209I variants, whereas strong consecutive staining was observed in patients without these variants. Moreover, more number of DKD variants were identified in probands than in their parents with MODY.

CONCLUSIONS

The genetic effect of more pathogenic variants in various DKD susceptibility genes, especially variants in the COL4A3 gene, partially explained the more severe kidney phenotype in probands with kidney biopsy-proven DKD.

Monogenic Diabetes in Children and Adolescents: Recognition and Treatment Options

PURPOSE OF REVIEW

We provide a review of monogenic diabetes in young children and adolescents with a focus on recognition, management, and pharmacological treatment.

RECENT FINDINGS

Monogenic forms of diabetes account for approximately 1-2% of diabetes in children and adolescents, and its incidence has increased in recent years due to greater awareness and wider availability of genetic testing. Monogenic diabetes is due to single gene defects that primarily affect beta cell function with more than 30 different genes reported. Children with antibody-negative, C-peptide-positive diabetes should be evaluated and genetically tested for monogenic diabetes. Accurate genetic diagnosis impacts treatment in the most common types of monogenic diabetes, including the use of sulfonylureas in place of insulin or other glucose-lowering agents or discontinuing pharmacologic treatment altogether. Diagnosis of monogenic diabetes can significantly improve patient care by enabling prediction of the disease course and guiding appropriate management and treatment.

Prenatal iron exposure and childhood type 1 diabetes

Iron overload due to environmental or genetic causes have been associated diabetes. We hypothesized that prenatal iron exposure is associated with higher risk of childhood type 1 diabetes. In the Norwegian Mother and Child cohort study (n = 94,209 pregnancies, n = 373 developed type 1 diabetes) the incidence of type 1 diabetes was higher in children exposed to maternal iron supplementation than unexposed (36.8/100,000/year compared to 28.6/100,000/year, adjusted hazard ratio 1.33, 95%CI: 1.06-1.67). Cord plasma biomarkers of high iron status were non-significantly associated with higher risk of type 1 diabetes (ferritin OR = 1.05 [95%CI: 0.99-1.13] per 50 mg/L increase; soluble transferrin receptor: OR = 0.91 [95%CI: 0.81-1.01] per 0.5 mg/L increase). Maternal but not fetal HFE genotypes causing high/intermediate iron stores were associated with offspring diabetes (odds ratio: 1.45, 95%CI: 1.04, 2.02). Maternal anaemia or non-iron dietary supplements did not significantly predict type 1 diabetes. Perinatal iron exposures were not associated with cord blood DNA genome-wide methylation, but fetal HFE genotype was associated with differential fetal methylation near HFE. Maternal cytokines in mid-pregnancy of the pro-inflammatory M1 pathway differed by maternal iron supplements and HFE genotype. Our results suggest that exposure to iron during pregnancy may be a risk factor for type 1 diabetes in the offspring.

The Distribution of Different Types of Diabetes in Childhood: A Single Center Experience

OBJECTIVE

Type 1 diabetes (T1D) is the most common cause of diabetes in childhood but type 2 diabetes (T2D) and maturity onset diabetes of the young (MODY) are emerging as noteworthy causes of diabetes at young ages. The aim is to determine the distribution, trends and clinical features of the different types of diabetes in childhood in one tertiary center.

METHODS

The records of children and adolescents aged 0-18 years who were diagnosed as “diabetes/persistent hyperglycemia” between January 1999 and December 2016, were reviewed. Clinical and laboratory characteristics of the patients at diagnosis and type of diabetes were recorded.

RESULTS

The mean ± standard deviation age of 835 patients (48.7% females) at diagnosis was 8.8±4.4 years. Eighty-four percent of the patients were diagnosed as T1D, 5.7% as T2D, 5.3% as clinical MODY and 5% as being cases of other types of diabetes. The frequency of diabetic ketoacidosis (DKA) and severe DKA in T1D were 48.4% and 11.6%, respectively. Fourteen patients (29.2%) with T2D presented with ketosis and two of them (4.2%) had DKA at diagnosis. Antibody positivity was 83.1% in T1D and 14.8% in T2D. A statistically significant increase in the frequency of T2D has clearly been demonstrated in recent years with a frequency of 1.9%, 2.4% and 7.9% in 1999-2004, 2005-2010 and 2011-2016, respectively (p<0.001). In MODY, genetic analysis was performed in 26 (59%) patients and HNF1A and GCK gene mutations were detected in 3 (11.5%) and 14 (53.8%) patients, respectively.

CONCLUSION

Although the most frequent cause of DM is T1D in childhood, a trend towards increase in the frequency of T2D in recent years is notable in our population.